The Hong Kong Arts Festival (HKAF) has long been one of the most high-profile cultural activities in the region. For thirty seven years, performers of various art have showcased their talents here, delighting audiences with the wide spectrum of arts on offer each year

Ever since the commissioning of the Hong Kong Cultural Centre (HKCC), most of the shows of HKAF have been scheduled in venues inside it, the most active being the HKCC Concert Hall. This natural-sounding, acoustically-optimised concert hall has reflective panels to amplify live orchestral performances. It seats 2000, mainly in the stalls and main balcony areas, with one quarter of the audience on side balconies and rear balconies.

   In most cases, large symphonic orchestras rely on the highly reverberant natural acoustics of the Hall, but, for low-volume musical pieces requiring microphone pick up or electro-acoustically amplified bands, the hall presents a real acoustic engineering

长久以来,每年一度的香港艺术节都是香港文化艺术活动的重

要节目.37年来,香港艺术节当局所安排多姿多彩的艺术节木, 及从世界各地邀请来港演出的嘉宾,都从没令观众失望过.自从

香港文化中心落成启用后,多项的演出也移师此地,其中的音乐

厅更是音乐类别的首选场地,因此也是艺术节表演活动的重心.

香港文化中心音乐厅,座位2000个,座席360度四面包围表演台, 正面座席占7成,二层舆两侧及台后座席连贯.(见下图).它是一

个以现场声声学设计而成的音乐厅, 因此拥有众多的声学反射

板把表演台的现场声反射扩大. 在大部份管弦乐跟较强声的乐

器演出是相当称职的,但当一些弱声乐器演出时,后排座席听众

就感到声量水平不足了, 必需使用电声拾音再于扩声系统放送

来辅助.

由于该厅现有扩声系统原设计以公告为主,声为辅,并没有为投放大声压时作过设计的优化.因此,在大多数需要较大声压水平

challenge. The in-house system, a single mono cluster, is not able to deliver adequate SPLs and is primarily used for announcements, and musical playback with lower SPL demands. For amplified band performances, an additional sound reinforcement system must be bought in, usually contracted from a local rental company.

   The organiser of HKAF has depended for years on a very traditional PA system, stacked Left-right on the stage, supplied by a local rental company that has sponsored the events for many years. Year after year, complaints were received about the poor sound performance of this system, particularly its low intelligibility and insufficient musicality, a consequence of the difficulties of using a stacked system configuration in this highly reverberant venue.

    MISO TECH CO.LTD., one of the production houses working on performances for HKAF, felt that something could be done about the problem, so they recommended Top Plot International Ltd., NEXO distributor for China, Hong Kong & Macau, to design an acoustically optimized solution for this venue, a compact system, as fast to rig as possible, to meet the constraints of the venue. A test event was arranged to verify the solution some months before the HKAF. A pop concert provided the chance to try the system at high SPL.  To tackle the acoustic problems, the system first needed to take account of both vertical and horizontal directivity control for all the different seating areas in the venue.

的电扩声演出时, 都会由音响租赁公司提供主扩声系统.以往,香

港艺术节主办当局依靠一间本地音响租赁公司提供的音响器材,

它们所提供是传统式,台侧叠合远场+近场+指向性低频音箱的主扩

声系统,显然没法对应这场地的声学条件而效果极为恶劣,

多年来,主办单位承受了很多听众的投诉. 香港的制作公司美仕

特科娱有限公司(MISO TECH CO. LTD.), 近年都参与协助香港

艺术节部份的演出, 觉得应该可以改善这问题, 所以特找来法国

NEXO力素的中港澳总代理, 天博国际有限公司TOP PLOT INTL. LTD.,提供解决方案, 并在艺术节之前数个月, 于此馆的一场电

声流行乐演出来测试解决方案的实际表现.

解诀方案的重点在垂直及水平两面的覆盖下功夫., 首先左及右主

扩声选用了力素最新的GEO S12系统, 每阵列配置为4只S1210 + 2只S1230的垂直线阵列. 其吊挂高度及垂直投射角度的选置为刚

好是覆盖从前排座席至包厢顶最后排座席, 而下层最后排的座席

则刚没有被突出的包厢底部遮蔽了主扩声的直达途径. 但两翼

侧包厢底的补声还是需要的.主扩声的水平覆盖面也作了些特别安排, 线阵列上面4只的S1210都装置了80° 水平角度板,而下面

2只的S1230装置了120° 水平角度板.这安排的原因是减少主

扩声投射到众多的反射板, 从宜避免主声大量的返射折回表演

台. 所有的覆盖面及角度都经力素原厂线阵列设计软件模拟而

设定核实. 至于在表演台两侧的包厢坐席, GEO S12, 就使用了

相同的双箱的S12系列音箱,但因为所覆盖的座席行数只若十行,

Main FOH rigs of NEXO S12 line arrays were rigged at left and right of front of stage, 4x GEO S1210 + 2x S1230 per array were used. The chosen angles and height were such that for the vertical spray, angled from the front row to the last row upon balcony, and also enough to get thru to the back rows under balconies. NEXO PS8 front fills were used to lower the sound images for the front rows. Under-balcony side fills are still needed at the two wings because of the masking effects of the side balconies on the FOH main system.

On the horizontal plane, the top four boxes were installed with 80° flanges and the two lower boxes were 120 ° flanged. The design was verified by NEXO GEOsoft2 Line Array Simulation software. The aiming of the two FOH line array beams was away from most of the reflecting panels, thus avoiding huge amount of direct reflections. At each side and rear balconies were point-source clusters of two S12 modules, blending coverage seamlessly with the FOH system. The rear clusters include one S1210 10° cabinet, and one S1230 30° cabinet. . These hit the rear balconies with 20 to 40 degrees of vertical coverage, just enough to cover the seats and narrow enough to avoid reflections from the wall panels surrounding these balconies.

For low frequencies, the system uses the NEXO RS15 Ray Sub, a cardiod subwoofer with high directivity and beam pattern control. At each side of the front of stage are 3x RS15 in alternate mode, that is, one on top of the other facing in allternate directions. The stacks were turned 90 degrees pointing towards the front audiences. Instead of the usual practice of speaker drivers facing the audience, in this configuration they point outwards to the audience and inwards to the stage. This might looked strange, but actually, the bass pattern control relies on both processor algorithm and the physical positions of cabinets. By applying directional bass control, it is much easier to minimize the LF acoustic reflections, which occur a lot at high SPLs when using standard omni-directional sub-bass systems. Another advantage is that the VLF spills on the stage were much lower and therefore created less background noise in microphone and acoustic pickups.

The rear and side balconies were so close to the performer that their LF coverage were much less demanding, and these S12s could be set up in full range mode, able to play down to 50Hz.

The test event went perfectly and Top Plot's designs were accepted for HKAF 2009. Three jazz groups, Chick Corea and John McLaughlin, Omar Sosa and Lisa Ono, giving a total of six performances, were scheduled to use the NEXO S12 system in the Concert Hall.  

Sound Reinforcement Equipment List:

FOH main left & right:

                      NEXO GEO S1210 x4 + S1230 x2 per line array
Side Fills left & right:

                     NEXO S1210 x1 + S1230 x1 per twin mounting
Rear Fills:        NEXO S1210 x2
Under Balconies Fills:

                     NEXO S1230 x3 in triple mounts per side
Front Fills:       NEXO PS8 x4 on stage floor
Sublow:           NEXO RS15 x3 in directional mode per side.

Powered Controllers:
                 NEXO NXAMP 4x1, 4Channel power amp. x7 pcs.
                 NEXO PS8AMP, 2/3 channel power amp.   x1 pcs

Comments from members of the performing groups, sound engineers, the venue technical manager and organizer were all extremely positive, and only very minor further issues were raised - and quickly handled. Patrick Destandeau, the German sound engineer for Omar Sosa, was especially happy with the directional subs; these gave very little LF spill onto the stage and thus very clean mic pickups. Yet he commented that the under-balcony seats should be covered better, resulting in Top Plot bringing in 4x additional GEO S1230 boxes to set as arc point source systems for the stage wings. He also proposed that the FOH position should be located further away from the back walls and these suggestions will be put in action at the next HKAF.

During rehearsal, musicians in Chick Corea's band actually walked around the audience seats to feel the effects while playing their instruments with wireless pickups, giving a "thumbs up" response.

During the Lisa Ono performance, another LF sound field control configuration was used, with both RS15 rigs facing outwards to the their sides. The bass patterns were steered inwards slightly less than 30 degrees, and the bass quality became more solid and firm to cope with Lisa's featured soft Bossa Nova style. Under-balcony fills in the wings were changed to 3x S1230s per side , a lesson learned from the previous show. These additions help bala场nce the mid-high frequencies near the sub stacks, and noticeably increased under-balcony coverage.

Mr. Taka Saito, sound engineer for Lisa Ono, has been with the group for ten years. He's no stranger to NEXO systems back in Japan, but this is the first time he had mixed on the GEO S12. His comments were that the system gave very clean definition, the line array system was well aimed to avoid reflections, the LF didn't resonant much at and beyond the working sound pressures levels. Overall he thinks this is amazing because this concert hall was designed for natural live sound acoustically.

Nicolas Kirsch, Sales Manager for Nexo Asia, attended several of the concerts to see for himself what had been achieved. "I have been attending the HKAF jazz and world music concerts for over 10 years, they have really great programming, but they've always used this hall which is best suited for classic orchestras. This is the nicest large auditorium in HK and sponsors like it. So there was no other way to approach the project other than by very scientifically designing a system that would improve sound quality to, say, 70-80% of the maximum achieveable (considering you cannot change the venue acoustics, seating arrangements, hanging points, max lifting loads etc), and then, by a series of small changes in the configurations and DSP programming, bringing that performance level up 90-95%.

"We're very happy with what we've heard and what we've learned. I am so glad, it's the first time I can really sit and relax at concerts in this room, listening to great sound, and eventually forgetting about the audio and just diving into the artist performance. This is what it should be about. Now with a sound like that, the HK Concert Hall is really a great room. I give all my thanks to the supports from Top Plot.  

Key persons : HKCC Venue Technical Manager, Mr. Peter Li, HKAF Sound Coordinator, Mr. Anthony Leung, HKAF Program Director, Ms. Grace Lang.

Ms Grace Lang, who had initiated the drive to improve sound quality at the Concert Hall, had personally monitored all rehearsals and performances, and attended all shows to understand the changes taking place. She was very satisfied with the new sound system and by the quality of support provided by Top Plot. As she puts it, "we haven't had a single complaint this year!" The pay-off made all the changes and efforts worthwhile and HKAF2009 Concert Hall performances concluded with a crowd-mad concert from Lisa Ono, putting the Hong Kong audience on their feet. All in all, HKAF2009 ended with excellent artists' performances and sound qualities, and are looking forwards for a repeated success next year.

所以无需配置成垂直阵列,而是采用了双箱的"U"字吊挂架把两只S12垂直吊挂,不过,箱子的安排还是经考虑设置的, 上的

一只是S1210, 垂直10°较远投的音箱, 并安装上水平80°的

角度板. 底部的是S1230,垂直30°, 近场的音箱, 并安装上

水平120°的角度板. 这是NEXO力素GEO S12系列的其中一

个特点:可配置成垂直线阵列或单,双及多只音箱组成的系统. 这配置也是从减小投射往座席前后的返射板为主,另一益处是

主扩声跟侧补声用了同一系列音箱,两系统连接点的缝合更为

完善. 至于表演台后听众席区,因为比侧座席区的距离较远而

座席行数也较小,所以就配置了2只1210,垂直10°.远投音箱, 估计这方面的返射可能较严重, 需要收窄一点垂直的覆盖面.

低频音域的安排就配置使用了法国NEXO力素RAY SUB指向性低

频音箱的系列首发形号RS15,它拥有极佳的低频音场控制. 在两表演台侧前方地面安放3只RS15低频音箱阵列,音箱正反的互叠起了(见左图),音箱的其一侧面面向正面听众席,跟一般传统低频音箱单元面向正前方有所不同, 并可能对不明解

因由的人觉得有点怪异. 其实这是力素Ray Sub指向性低频

音场的一个操控的模式, 这操控性需依靠音箱之间物理位置

关系跟处理器的程式运算结合而成的.正确地配置并操控了低频音

场的方向性就较易减小低频的反射及大声压时的回响共鸣,相对于

全向性低频系统, 指向性系统于表演台中的低频溢漏更是微小,拾

音更清晰, 啸叫的主要成因素:啸叫前的增益(gain before feedback)最少可添6个分贝以上.弱声的拾音而大声压的播送都不再是重大困难, 连带现场录音或转播的质素都大大提升了.         大家可以发觉指向性低频系统只指向正前方听众席, 后方及侧方

包厢座席没有专设的低频系统覆盖.原因是这些座席跟表演台距离很近,一般来说大部份乐器电扩声均可直达只,再加上覆盖该区的

S12是配置在全频模式,低频可下达至50Hz.(需不需要专设低频系

统来覆盖由演出类别作考虑,就算要用也只需小量配置便可).

测试演出的效果令人满意相当不错,所以当局诀定于2009年艺术

节采用这个系统.最后定下了三个爵士乐队: Chick Corea & John Mclaughlin, Omar Sosa 及 小野丽莎(Lisa Ono)共6场演出于该

音乐厅

 三个乐队的风格各异, Chick Corea为美国老牌爵士乐队, 哑低

音结它(fret bass)及鼓节奏沉而强劲. Omar Sosa 为非州节奏

爵士乐的代表, 并辅以很新鲜丰富的口技, 令人拍案叫绝. 小野

丽莎则是五十年不变的以Bossa Nova轻柔低诉, 带动一些些心

底里的忧怨.

表演及采排前后得到了一些有关人仕; 乐队成员, 音响工程师, 会场技述经理, 艺术节当局高层人仕, 对系统感觉和意见, 大部份

的回应都是正面, 但也有一些次要的地方可能需要改进. Patrick Destandeau先生,是Omar Sosa的音响工程师, 他说他最喜欢这指向

性低频系统的应用, 表演台上拾音器(pickups)所捡到的低频溢漏

极小, 所以音色很乾净清晰,.但相信包厢底下的座席区应可作更佳

的覆盖, 而主扩声混音台位置应远离后墙多一些, 以免影响混音的

判段. 整个系统的配合,有效地对应着场地的声学条件发挥出来了. 在Chick Corea乐队采排时, 队中的一些成员,经常跑上听众席各

区一面以无线拾音的乐器演奏, 一面亲身体验扩声系统的性能, 最后问及他们的反应时, 都是树起了大姆指说顶好, 但也同样提出

了混音台位置的意见.在结合了之前的一些意见后,决定在小野丽莎

的演出作了一些改进. 首先得悉小野丽莎音乐的风格较柔而低频较

弱而沉, 所以低频系统更改了音场控制模式, 从三只正反互叠改为

三只面对同一方向, 向其外侧发射. 在这模式下, 低频音场会指

向内30°, 而音质较润而刚实一些, 能够对小野丽莎的轻柔Bossa Nova风格作补偿作用. 在两翼包厢底部的补声系统, 也作出一些修

改, 每边增至3只S1230, 水平座地安放, 共90°的水平覆盖. 增加

的音箱数量,刚好平衡了高中频对低频因指向模式音场更改的比例变化. 斋藤隆明先生(Taka Saito), 是小野丽莎的音响工程师, 跟

随乐队十年有多了, 他比较喜爱做监听混声位置的工作. 过去, 他

在日本也曾多次使用法国力素的系统, 但尚未使用过新的GEO S12

系统, 这可算是首次了. 他认为系统的分析力很高, 而主扩声线

阵列正确地避开众多的反射板,低频在高声压水平时没有感到回响的共鸣, 对于本身是现场声学设计的音乐厅来说,简直是有些惊喜!

   力素亚洲经理Nicolas Kirsch(黎高), 十年来每年都是艺术节

其中几个项目的听众, 他认为香港艺术节有很好的节目, 并经常使

用该音乐厅作古典乐演出用途.是该类演出之最佳场地.在这种场地

的声学设计条件作电声演出, 如果在不能改变声学设计,坐席安排,

系统吊挂点和重量上限等等下,使用一些科学化的方法来提升到七至八成的现场演出性能已是很不错了. 现在, 我们只是使用了较合

理的系统和配置, 适当的覆盖和DSP调整提升便提升达九成以上的

性能实在很棒.

    艺术节主要的一众有关人等: 主办单位当局的节目总监,

梁掌玮女仕, 当局的技述顾问, Anthony Leung, 香港文化中心

技述监督, 李炳强先生等, 在采排及现场演出时亲身体验系统

的优选性能,都觉得大家今年在艺术节前所付出大量的前期工作努力没白费的,高水平的艺术演出自必然需要高质素的系统来配合, 今年艺术节结束了, 回响还在脑子里,投诉可还未听到, 大家已在

期待明年的艺术节的来临了.

主要器材清单:

主扩声左及右线性阵列:

              每阵列NEXO力素 GEO S1210 x4只 + S1230 x2只

侧补声左及右: 每边NEXO力素 S1210 x1只 + S1230 x1只 后座席区补声: NEXO力素 S1210 x2只

包厢底补声:   每边NEXO力素 S1230 x3只

前台补声:     NEXO力素 PS8 x4只

超低频系统:   每边NEXO力素RS15 x3只.

功放及处理器:

      NEXO力素 NXAMP 4x1, 4通道带数码TD处理器功放 x7台.

      NEXO 力素PS8AMP, 2/3 通道带PS8TD处理器功放   x1台